A founder mutation of the BRCA1 gene in Western Sweden associated with a high incidence of breast and ovarian cancer

The aim of this study was to describe and characterise a founder mutation o f the BRCA1 gene in western Sweden. Of 62 families screened for BRCA mutati ons, 24 had BRCA1 mutations and two had BRCA2 mutations. Tumours that occur red in family members were histologically reviewed and mutational status wa s analysed using archival paraffin-embedded tissues. The same BRCA1 mutatio n, 3171ins5, was found in 16 families who were clustered along the western coast of Sweden. Mutation analysis revealed a maternal linkage in 13 famili es and a paternal linkage in 3. There was complete agreement between mutati on analysis results obtained from blood and archival tissues. The penetranc e of breast or ovarian cancer by age 70 years was estimated to be between 5 9 and 93%. There were no differences in survivals between breast or ovarian cancer patients with the mutation and age-matched controls. Thus, a predom inant BRCA1 gene founder mutation associated with a high risk of breast and ovarian cancer has been identified and found to occur in a restricted geog raphical area, thereby allowing timely and cost-effective mutation screenin g using blood samples or archival histological material. (C) 2001 Elsevier Science Ltd. All rights reserved.